rebase: keep original mq patch format (Issue1574)
Rebase now doesn't make assumptions about which format has been
used for a mq patch (git or normal).
Before finalizing a patch it keeps track of the original format,
by reading its header, and then restores the format when reimporting
it.
This way it also allows for having mixed styles.
Note: this version corrects a failure in the test
0
0
adding changesets
transaction abort!
rollback completed
killed!
.hg/00changelog.i .hg/journal.branch .hg/journal.dirstate .hg/requires .hg/store .hg/store/00changelog.i .hg/store/00changelog.i.a